Localized surface plasmons have been observed since the Romans who used gold and silver nanoparticles to create colored glass objects such as the Lycurgus Cup (4th Century AD). A gold sol in the British museum, created by Michael Faraday in 1857, is still exhibiting its red color due to the plasmon resonance at ˜530 nm. In more recent times, localized plasmons have been observed on rough surfaces and in engineered nanostructures and have led to the observation and exploitation of Surface Enhanced Raman Scattering (SERS) and new tunable plasmon structures with potential applications in biology and medicine.